Symbiosis, Parasitism and Bilingual Cognitive Control: A Neuroemergentist Perspective

Interest in the intersection between bilingualism and cognitive control and accessibility to neuroimaging methods has resulted in numerous studies with a variety of interpretations of the bilingual cognitive advantage. Neurocomputational Emergentism (or Neuroemergentism for short) is a new framework for understanding this relationship between bilingualism and cognitive control. This framework considers Emergence, in which two small elements are recombined in an interactive manner, yielding a non-linear effect. Added to this is the notion that Emergence can be captured in neural systems using computationally inspired models. This review poses that bilingualism and cognitive control, as examined through the Neuroemergentist framework, are interwoven through development and involve the non-linear growth of cognitive processing encompassing brain areas that combine and recombine, in symbiotic and parasitic ways, in order to handle more complex types of processing. The models that have sought to explain the neural substrates of bilingual cognitive differences will be discussed with a reinterpretation of the entire bilingual cognitive advantage within a Neuroemergentist framework incorporating its neural bases. It will conclude by discussing how this new Neuroemergentist approach alters our view of the effects of language experience on cognitive control. Avenues to move beyond the simple notion of a bilingual advantage or lack thereof will be proposed

Consequences of late bilingualism for novel word learning: evidence from Tamil–English bilingual speakers

Aims and objectives: Recent studies that have investigated novel word learning have demonstrated an advantage for bilinguals compared to monolinguals. The study reported here sought to explore whether a word learning advantage is revealed only for early bilinguals with comparable proficiency in both their languages, or whether such advantages are also observed in individuals with relatively late experience of, and less proficiency in, a second language. Methodology: We tested the acquisition of novel words in an unknown language using identification and naming tasks in three groups of 20 participants: monolingual Tamil speakers; early Tamil–English bilingual speakers; and late Tamil–English bilingual speakers. Data and analysis: The data was analysed using a non-parametric Kruskal–Wallis test followed by linear regressions. Findings: The results showed a bilingual advantage for word learning as evidenced by superior performance in both the naming and identification tasks and, critically, late bilinguals outperformed monolinguals. Originality: The results of the present study revealed, for the first time, a bilingual advantage in word learning even when individuals acquire their second language later in life. Significance: The results suggest that the positive effects of bilingualism may generalise beyond non-linguistic tasks, perhaps affecting a general language learning mechanism. Moreover, this seems to occur even in late bilingualism. This is in contrast to the reported effects on cognitive control mechanisms that show only weaker advantages for individuals who learned a second language later in life

Individual language experience modulates rapid formation of cortical memory circuits for novel words

Mastering multiple languages is an increasingly important ability in the modern world; furthermore, multilingualism may affect human learning abilities. Here, we test how the brain’s capacity to rapidly form new representations for spoken words is affected by prior individual experience in non-native language acquisition. Formation of new word memory traces is reflected in a neurophysiological response increase during a short exposure to novel lexicon. Therefore, we recorded changes in electrophysiological responses to phonologically native and non-native novel word-forms during a perceptual learning session, in which novel stimuli were repetitively presented to healthy adults in either ignore or attend conditions. We found that larger number of previously acquired languages and earlier average age of acquisition (AoA) predicted greater response increase to novel non-native word-forms. This suggests that early and extensive language experience is associated with greater neural flexibility for acquiring novel words with unfamiliar phonology. Conversely, later AoA was associated with a stronger response increase for phonologically native novel word-forms, indicating better tuning of neural linguistic circuits to native phonology. The results suggest that individual language experience has a strong effect on the neural mechanisms of word learning, and that it interacts with the phonological familiarity of the novel lexicon.Mastering multiple languages is an increasingly important ability in the modern world; furthermore, multilingualism may affect human learning abilities. Here, we test how the brain’s capacity to rapidly form new representations for spoken words is affected by prior individual experience in non-native language acquisition. Formation of new word memory traces is reflected in a neurophysiological response increase during a short exposure to novel lexicon. Therefore, we recorded changes in electrophysiological responses to phonologically native and non-native novel word-forms during a perceptual learning session, in which novel stimuli were repetitively presented to healthy adults in either ignore or attend conditions. We found that larger number of previously acquired languages and earlier average age of acquisition (AoA) predicted greater response increase to novel non-native word-forms. This suggests that early and extensive language experience is associated with greater neural flexibility for acquiring novel words with unfamiliar phonology. Conversely, later AoA was associated with a stronger response increase for phonologically native novel word-forms, indicating better tuning of neural linguistic circuits to native phonology. The results suggest that individual language experience has a strong effect on the neural mechanisms of word learning, and that it interacts with the phonological familiarity of the novel lexicon.Peer reviewe

The neural correlates of semantic richness : Evidence from an fMRI study of word learning

We investigated the neural correlates of concrete nouns with either many or few semantic features. A group of 21 participants underwent two days of training and were then asked to categorize 40 newly learned words and a set of matched familiar words as living or nonliving in an MRI scanner. Our results showed that the most reliable effects of semantic richness were located in the left angular gyrus (AG) and middle temporal gyrus (MTG), where activation was higher for semantically rich than poor words. Other areas showing the same pattern included bilateral precuneus and posterior cingulate gyrus. Our findings support the view that AG and anterior MTG, as part of the multimodal network, play a significant role in representing and integrating semantic features from different input modalities. We propose that activation in bilateral precuneus and posterior cingulate gyrus reflects interplay between AG and episodic memory systems during semantic retrieval

Does bilingualism come with linguistic costs? A meta-analytic review of the bilingual lexical deficit

A series of recent studies have shown that the once-assumed cognitive advantage of bilingualism finds little support in the evidence available to date. Surprisingly, however, the view that bilingualism incurs linguistic costs (the so-called lexical deficit) has not yet been subjected to the same degree of scrutiny, despite its centrality for our understanding of the human capacity for language. The current study implemented a comprehensive meta-analysis to address this gap. By analyzing 478 effect sizes from 130 studies on expressive vocabulary, we found that observed lexical deficits could not be attributed to bilingualism: Simultaneous bilinguals (who acquired both languages from birth) did not exhibit any lexical deficit, nor did sequential bilinguals (who acquired one language from birth and a second language after that) when tested in their mother tongue. Instead, systematic evidence for a lexical deficit was found among sequential bilinguals when tested in their second language, and more so for late than for early second language learners. This result suggests that a lexical deficit may be a phenomenon of second language acquisition rather than bilingualism per se

Early recovery profiles of language and executive function in bilingual persons during the first twelve weeks post brain injury

Background: The nature, rate and pattern of recovery in bilingual persons following brain damage has been investigated over many years but several controversies remain. Recent evidence suggests that the relationship between executive function (EF) processes and language recovery may be distinct in bilinguals. An improved understanding of such underlying linguistic and cognitive processes may enhance assessment and treatment particularly in the acute phase. There is limited knowledge regarding how these processes interact in the acute phase and there remains little guidance as to the choice of an appropriate assessment battery for bilinguals. In the South African context, bilingual persons with a brain injury are often treated as monolinguals due to the language challenges and the lack of standardised assessments. Thus there is a need to develop a simple, effective battery which is able to differentiate aetiologies, is sensitive to recovery processes, and in a multicultural and multilingual context is able to distinguish normal from pathological profiles. Aims: The research study aimed to identify an assessment battery for language and EF that is sensitive to etiology and the recovery process for South African bilingual persons who have had a neuronal insult. It also aimed to evaluate the linguistic and executive function skills of bilingual patients with acquired neurological communication disorders (ANCD) at two time periods within the first 12 weeks post injury. A further aim was to profile the recovery of bilingual persons with ANCD in the acute recovery phase according to etiology (Right CVA, left CVA and TBI). Method: A multivalent comparison study with a longitudinal component was conducted at two acute rehabilitation centres. A convenience sample of 29 bilingual, second language English speaking participants (19 with a cerebral vascular accident (CVA) and 10 with a traumatic brain injury (TBI)) were assessed at two time periods within the first 12 weeks post injury. They were assessed using the Comprehensive Aphasia Test (CAT) and a nonverbal EF battery. The nonverbal battery comprised tasks to assess updating (n-back task), mental shifting (number-letter task; Wisconsin Card Sorting test), and inhibition (Victoria Stroop; Tower of Hanoi). A control group of 19 neurologically intact bilingual, second language English speakers who were matched according to age and education level were assessed employing the same battery. The control group completed an initial assessment and then were reassessed six weeks later. Results: The CAT was found to be a suitable assessment measure when assessing bilingual, second language English speakers in the South African context. A between- group analysis identified statistically significant differences between etiologies (including the control group) for language assessment as well as the EF assessment, indicating the battery was able to differentiate normal from pathological individuals. While most of the test battery was found to be suitable for the participants, the Tower of Hanoi and the number-letter task were deemed inappropriate for the population and the cultural context. Overall the battery of tests distinguished between aetiologies, testing period (first and second) and pathological from normal individuals. It was found that this battery was appropriate for a variety of cultural groups. A within- group analysis determined that there were unique profiles of language and EF skills according to etiologic and that different profiles of change emerged according to each etiology for both language and EF subtests. Discussion: The streamlined battery that was found to be beneficial and sensitive to the multicultural and multilingual nature of South Africa comprised the CAT as the language assessment and the n-back task (updating), Victoria Stroop (inhibition) and WCST (shifting) comprised the EF assessment battery in the acute phase. This study confirms prior research on recovery processes in language across the three aetiologies but also highlights changes in executive functioning which may offer some explanations for differential recovery profiles. The results highlighted that inhibition may be a preserved bilingual advantage in participants with a right CVA or TBI. However, it was a deficit in participants with a left CVA. The role of inhibition may support the decision making process with regards to the language for therapy. Thus the EF profiles may also assist a clincian to determine whether to undertake monolingual or bilingual therapy There were also distinct relationships between language skills and EF skills for each etiology according to time frame. This provided insight into the interactions between language and EF during the acute phase of recovery. Knowledge of the specific EFs that interact with language recovery per etiology can assist a clinician in providing effective therapy in the acute phase that complies with neuroplasticity principles. Conclusion: Language assessment and treatment in the acute phase needs to be provided in combination with an understanding of recovery patterns, what is driving that pattern, and which cognitive deficits are contributing to the language behaviour. In addition clinicians need to be aware of the impact of updating, shifting and inhibition in a bilingual person as well as the role bilingual advantage may have in decision making for therapy, the recovery process and as a possible tool to support the therapeutic process

Examining the Paradox of Adult Second Language Word and Grammar Learning

Background: Adults generally demonstrate advanced cognitive skills compared to children, with second language (L2) learning being a key exception, particularly within the grammar domain. As optimal vocabulary and grammar learning are believed to engage in distinct explicit and implicit learning mechanisms, respectively, the advanced neurocognitive mechanisms underpinning adults’ higher-order cognitive skills may particularly interfere with implicit grammar learning. The objective of this dissertation was to examine select neural and cognitive factors that may contribute to word and grammar learning differences. In Study 1, I investigated the neural correlates of artificial vocabulary and morphology learning using functional Near-Infrared Spectroscopy (fNIRS). Despite adults outperforming in explicit vocabulary outcomes compared to implicit grammar generalization, cortical differences between processing the two language components were minimal. On the other hand, significant changes in neural activity were observed in all four cortical lobes over the course of the initial language learning period, demonstrating the widespread cortical engagement inherent in the process of L2 learning. In Study 2, I examined the impact of effortful learning on implicit word and grammar learning outcomes using a modified statistical language learning paradigm with an underlying grammatical pattern. Performance on speeded syllable detection tasks using familiar and unfamiliar targets revealed that effortful and passive learning conditions resulted in comparable implicit learning outcomes related to word segmentation and grammar generalization. Thus, directing effort towards learning neither facilitated nor interfered with implicit L2 attainment. In Study 3, I investigated whether individual differences in statistical learning of words and/or grammatical patterns were related to domain-general cognitive abilities. The findings indicate that performance on tasks evaluating short-term memory, attention, strategic thinking, reasoning, and planning skills were not related to implicit word or grammar learning outcomes. Conclusion: Together, this dissertation presents empirical evidence that adults learn vocabulary more easily than grammatical patterns, but learning success is not related to domain-general cognitive mechanisms, at least concerning implicit representations of language. These findings are discussed in relation to existing literature and emerging theories of L2 learning. This research has important methodological implications and provides valuable insights to inform pedagogical practices for foreign language instruction

The search for a bilingual advantage in executive functions: a developmental perspective.

222 p.Bilinguals need very intensive language-control mechanisms to produce effective communication and avoid intrusions from the non-target language, because both languages are always active in a bilingual mind (Thierry & Wu, 2007), competing with each other. It is mostly assumed that bilinguals apply inhibition to the non-target language (see, for example, the IC model, Green, 1998). This constant need of inhibition makes bilinguals much better at their general inhibitory abilities as compared to their monolingual counterparts, as claimed by the bilingual advantage defenders (Bialystok et al., 2005). However, recent findings suggest that the repeatedly shown bilingual advantage effect in tasks tapping into domain general inhibition might stem from uncontrolled factors associated to bilingualism, rather than from bilingualism itself, as well as to small sample sizes (Paap & Greenberg, 2013). Crucially, previous evidence tended to neglect the importance of factors such as immigrant status or socio economic status. In the present thesis I aimed at testing the reliability of the criticisms to the bilingual advantage by testing large samples of carefully matched bilingual and monolingual children, young adults and seniors in sets of classic tasks that tap into domain general executive functions, such as Stroop, Flanker and Simon tasks. I found no indication of the bilingual advantage whatsoever, since every bilingual and monolingual group behaved comparably in every task, obtaining highly similar indices. The results are discussed and interpreted in the light of different perspectives.Basque Center on Cognition, Brain and Languag